Subsea soil preparation device and system

Abstract

Subsea soil preparation device (1), comprising a tool platform (2A, 2B), configured to be placed on and move along a seabed (SB); a soil combing tool (3) connected with the tool platform (2A, 2B), the soil combing tool (3) comprising a plurality of retractable blades (30), with at least an extended position and a retracted position, wherein, in the extended position of the plurality of retractable blades (30), at least a part of each of the plurality of retractable blades (30) extends into the seabed (SB) on which the tool platform (2A, 2B) is positioned, and at least in the extended position, the part of each of the plurality of retractable blades (30) that extends into the seabed (SB) is inclined with respect to the seabed (SB), and extends away from the tool platform (2A, 2B) in a front-facing direction.

Description

[0001] SUBSEA SOIL PREPARATION DEVICE AND SYSTEM

[0002] FIELD

[0003] The present disclosure relates to a subsea soil preparation device and a soil preparation system.

[0004] BACKGROUND

[0005] For purposes such as pipe and cable laying at the seabed, or the installation of other subsea utilities, often trenches are cut in the seabed such that these pipes or cables, or other utilities, can be buried - at least partially - in the seabed to protect the utilities from the underwater environment. The utilities can for instance be buried under soil or stone, or a combination thereof. The amount of effort involved with digging in the seabed is dependent upon the density and cohesiveness of the soil, and the amount and size of possible obstructions, such as boulders and the like. In addition, obstructions may prevent the utilities from reaching the desired burial depth. Accordingly, a seabed with a large amount of boulders, or other obstructions, may delay trenching operations to a significant degree. Also a seabed with densely packed soil may delay such operations. With rising costs of such operations, it would be beneficial to reduce the timespan of trenching or digging operations.

[0006] GB 2 573 588 A relates to a subsea clearance apparatus comprising a chassis, fore and aft skids spaced along a principal axis of the apparatus, a pair of flanks with a plurality of tines depending from the flanks. The tines are spaced transversely with respect to the principal axis and pitched toward the fore of the apparatus. In use, the chassis is spaced from the seabed by the skids as the apparatus is propelled therealong such that the tines engage and deflect away from the principle axis obstructions which are larger than a predetermined size and which protrude by a predetermined amount from the seabed. The orientation of the fore skids is adjustable to steer the apparatus and their height is adjustable to adjust the space between the tines and the seabed.

[0007] Further, in the apparatus of GB 2 573 588 A, the angle of the tines may be adjustable relative to the chassis using an actuator in order to vary the distance between the tips of the tines and the seabed.

[0008] SUMMARY

[0009] In view of the above, the present disclosure provides, according to a first aspect, a subsea soil preparation device, comprising a tool platform and a soil combing tool. The tool platform is configured to be placed on and move along a seabed. The soil combing tool is connected with the tool platform and comprises a plurality of retractable blades. The plurality of retractable blades has at least an extended position and a retracted position. In the extended position of the plurality of retractable blades, at least a part of each of the plurality of retractable blades extends into the seabed on which the tool platform is positioned. At least in the extended position, the part of each of the plurality of retractable blades that extends into the seabed is inclined at an inclination angle with respect to the seabed, and extends away from the tool platform in a front-facing direction. The retractable blades are configured to be extended and retracted relative to the tool platform through an actuation mechanism (in other words, the extension and retraction of the blades in independent from the tool platform), wherein the actuation mechanism is configured to extend and retract the retractable blades whilst substantially maintaining the inclination angle. Maintaining the inclination angle may involve maintaining the inclination angle in an inclination range. The inclination range may be plus or minus 10 degrees from the inclination angle, plus or minus 5 degrees from the inclination angle, or plus or minus 2 degrees from the inclination angle, or plus or minus 1 degree from the inclination angle. An average inclination angle of the part of each of the plurality of retractable blades that extends into the seabed with respect to a vertical axis, in the extended position, is a positive angle between 0 and 90 degrees. Accordingly, a normal of a frontfacing surface of the part of each of the plurality of retractable blades that extends into the seabed comprises a vertical component.

[0010] Preconditioning the seabed with a device according to the above significantly reduces the amount of time and effort required for subsequent trenching and / or digging in the seabed. Particularly, the soil combing tool allows for loosening and simultaneously filtering the soil through which the retractable blades are moved. As the blades are inclined, movement of the blades through the seabed naturally transports obstructions that cannot pass between the blades to the surface of the seabed, thereby making it easier for the obstructions to be removed during the subsequent trenching and digging operations. In addition the blades are retractable, such that the depth to which preconditioning is required - which may vary between operations - can be effectively selected. In further addition, due to the aforementioned inclination of the retractable blades, certain obstructions can be pulled upwards by retracting the inclined blades toward the surface, thus effectively clearing the trench that is to be dug. Roughly maintaining the inclination angle of the blades at each chosen depth of the blades through the actuation mechanism ensures combing efficiency. In other words, the inclination angle may be chosen to be optimal for the type of soil and / or the expected obstacles, such that the combing operation is as efficient as possible. Furthermore, as the blades are retractable and extendable with respect to the frame of the device, the center of gravity of the device is not affected. Furthermore, the depth of all blades can be controlled accurately. In other words, the device ensures that the cutting angle remains optimal at all penetration depths. The device allows for greater operational efficiency due to optimal cutting angles at all penetration depths and also eliminates instability caused by chassis movement during retraction in chassis-based systems. At greater penetration depths (e.g., 3m), lifting the chassis / platform results in excessive height, leading to significant stability issues. Particularly, the required penetration depth during the combing process varies significantly, for instance between 0.5 and 5 meters, or 1 to 3 meters, or the like. In case the penetration depth would be adjusted by tilting the blades, as is the case in the prior art, such large ranges of penetration depth would require very long blades, thereby increasing the size and weight of the actuator required for the tilting. In turn, the cutting angle would vary to a large extent. In case the penetration depth is adjusted by adjusting the heigh of the frame compares to the seabed, as is the case in the prior art, the center of gravity of the device would changes by meters, which is undesired for stability, and would require very long actuators (e.g., hydraulic legs), which would then have significant size and weight, which is also undesired.

[0011] Preferably, each of the plurality of retractable blades is at least partially curved or has a gradually increasing slope along at least a part of its length.

[0012] In the retracted position of the plurality of retractable blades, the plurality of retractable blades may extend at least partially above the seabed on which the tool platform is positioned, and preferably fully above the seabed on which the tool platform is positioned.

[0013] The soil combing tool may further comprise an unblocking member configured to reach between at least two of the plurality of retractable blades in the extended position and / or the retracted position thereof. Preferably the unblocking member is arranged between at least two of the plurality of retractable blades in the extended position thereof. Preferably, the unblocking member comprises a front-facing shield with a plurality of slits, wherein, each of the plurality of retractable blades extend through a respective one of the plurality of slits in the extended position of the plurality of retractable blades. Further preferably, the front-facing shield comprises one or more inclined surfaces having an inclination angle with respect to the front-facing direction. Even further preferably, the front-facing shield comprises two of the one or more inclined surfaces, wherein the two inclined surfaces form a V-shaped shield pointing in the front-facing direction. The unblocking member may comprise an actuator or robotic arm that can reach between at least two of the plurality of retractable blades in the extended position and / or the retracted position thereof.

[0014] An obstruction, such as a boulder, can get stuck between two blades thus forming a blockage. This negatively affects the speed at which the seabed can be prepared (i.e., preconditioned), as the device will encounter more resistance. The unblocking member effectively resolves such blockages. When the blades are retracted the blockage eventually reaches the unblocking member that is situated between the blades where the blockage has occurred. Accordingly, the blockage will be dislodged by retraction of the blades and the resulting contact with the unblocking member. The blades extending and retracting through slits in a shield-like element is an effective way of forming the unblocking member, as there is only a minimal gap between the unblocking member (i.e., the shield) and the blades. In addition, the shield prevents debris or obstructions from entering the tool platform. When the front-facing shield also comprises the one or more inclined surfaces, the obstructions are pushed away to the sides, thereby clearing the area for trenching or digging effectively. A V-shape is an effective shape for the shield, as the obstruction is then always moved to the side closest to the initial location of the obstructions, thereby clearing the area most efficiently.

[0015] The plurality of retractable blades may be tiltable with respect to the tool platform. Preferably, the blades are tiltable by means of a hydraulic mechanism. Particularly heavy obstructions that cannot be moved to the surface effectively through the inclined blades can be lifted to the surface by tilting the blades. In other words, an inclination angle of the retractable blades may be controlled, by tilting the plurality of retractable blades.

[0016] The subsea soil preparation device may further comprise an active cutting member, such as a rotatable cutting member, connected with the tool platform and configured to engage the seabed. Preferably, the active cutting member is tiltable between at least an engaged and a disengaged position, wherein in the engaged position the active cutting member engages the seabed, and preferably wherein in the disengaged position the active cutting member does not engage the seabed. In the case of a rotatable cutting member, a rotation axis of the rotatable cutting member is substantially perpendicular to the seabed in the engaged position, and preferably substantially parallel to the seabed in the disengaged position. Further preferably, in the engaged position, the active cutting member extends at least partially into the seabed. It is preferred that the plurality of retractable blades is positioned at a distance from the active cutting member in the front-facing direction, such that the active cutting member is located behind the plurality of retractable blades. As noted, the active cutting member can for instance be a rotatable cutting member (e.g., a drum cutter), or a chain cutter, a wheel cutter, another suitable active cutting member, or a combination thereof.

[0017] The rotatable cutting member may comprise at least one cutting element extending in at least a radially outward direction of said rotatable cutting member for engaging the seabed, wherein said rotatable cutting member is arranged to rotate around an axis of rotation, such that the at least one cutting element is arranged to move along a circumferential cutting path around the axis rotation having a predefined non-zero radius. The active cutting member may comprise a jetting unit, comprising at least one jet nozzle, preferably a plurality of jet nozzles, wherein said jetting unit is arranged for providing a flow of fluid to the at least one jet nozzle. In case the active cutting member takes the form of a rotatable cutting member, said at least one jet nozzle is preferably arranged, as seen in a two-dimensional plane perpendicular to the axis of rotation, within the circumferential cutting path and is configured for generating a fluid jet stream that is directed in ajet stream direction that comprises at least a radial outwardly directed component that is parallel to the radial direction with respect to the axis of rotation of said rotatable cutting member, such that, when in use, the at least one cutting element moves around the at least one jet nozzle and wherein, as seen in the two-dimensional plane perpendicular to the axis of rotation the fluid jet stream (and therefore also the jet stream direction) intersects with the circumferential cutting path.

[0018] Preferably, a number of jet nozzles of the plurality of jet nozzles are distributed along the length, as measured along the axis of rotation, of the rotating cutting member, so as to form ajet nozzle row and wherein the jetting unit comprises at least one jet nozzle row directed in a rearward direction having at least a component opposite a cutting direction of the cutting device, so as to provide a rearward evacuation flow in said rearward direction for evacuating the soil that has been cut away from the seabed by the rotatable cutting member in said rearward direction.

[0019] The soil combing tool may comprise a front-facing jet nozzle configured to generate a fluid jet stream directed substantially in the front-facing direction. Preferably, at least one retractable blade of the plurality of retractable blades comprises the front-facing jet nozzle. Further preferably, the at least one retractable blade comprises a plurality of front-facing jet nozzles.

[0020] The front-facing jet nozzles allow for fluidization of the soil bed of the seabed, thereby allowing the retractable blades to more easily move through jettable soils, such as sand. In addition, the jets may aid in keeping the blades clean from materials that tend to attach to the frontal surface of the blades.

[0021] The soil combing tool may further comprise a plurality of secondary blades connected to the tool platform, and wherein the plurality of retractable blades is positioned at a distance from the plurality of secondary blades in the front-facing direction, such that the plurality of secondary blades is located behind the plurality of retractable blades. Preferably, the plurality of secondary blades is retractable, with at least an extended position and a retracted position, wherein, in the extended position of the plurality of secondary blades, the plurality of secondary blades extend at least partially into the seabed on which the tool platform is positioned, and preferably wherein in the retracted position of the plurality of secondary blades, the plurality of secondary blades extends at least partially above the seabed on which the tool platform is positioned, and further preferably fully above the seabed on which the tool platform is positioned. Preferably, a first distance between each of the plurality of retractable blades in a direction perpendicular to the front-facing direction is larger than a second distance between each of the plurality of secondary blades in a direction perpendicular to the front-facing direction. The first distance may, for instance, be in the range of 10 cm to 150 cm. The second distance may, for instance, be in the range of 5 cm to 80 cm. Depending on the application and expected sizes of obstructions, these distances can be different. For example, the first distance can be in the range of 50 cm to 250 cm, and the second distance can be in the range of 10 cm to 150 cm.

[0022] The plurality of secondary blades may also be equipped with a unblocking member as described above in relation to the plurality of retractable blades of the soil combing tool.

[0023] Further preferably, the plurality of retractable blades and / or the plurality of secondary blades comprise force sensors configured to measure a movement resistance. The plurality of retractable blades and / or the plurality of secondary blades may be connected to the tool platform through at least one hydraulic mechanism, wherein the force sensors may comprise pressure sensors configured to measure a hydraulic pressure in the at least one hydraulic mechanism. Preferably, both the plurality of retractable blades and the plurality of secondary blades comprise the force sensors, such that the plurality of retractable blades measure movement resistant before soil preparation and the plurality of secondary blades measure movement resistance after soil preparation.

[0024] The force sensors allow for detection of resistance, which can be a valuable parameter to plot along an area or route that needs to be dug or trenched. Accordingly, it can more effectively be estimated what total trenching or digging effort is to be expected. Furthermore, providing both the retractable blades and the secondary blades with such sensors allows to measure the effectiveness of the soil conditioning by the soil preparation device itself, in situ. The difference in movement resistance at the retractable blades and at the secondary blades indicates the improvement in soil conditions for trenching or digging.

[0025] The subsea soil preparation device may comprise means for attaching a tow, such that the subsea soil preparation device may be towed along the seabed by a vessel. The subsea soil preparation device may also be couplable with a drag head of a suction hopper dredger, or to a suction pipe of such suction hopper dredger instead of the drag head.

[0026] At least part of the tool platform may be formed as a sled such that the tool platform may slide along the seabed, preferably comprising at least two ski-like elements extending substantially in the front-facing direction. The ski-like elements have upwardly sloped section at least at their front ends, so as to be able to deal with bumps and obstacles. The rear ends may also be provided with such upwardly sloped sections.

[0027] The subsea soil preparation device may comprise propulsion means, preferably wherein the propulsion means comprise at least one of a hydrojet, a propeller, driven tracks, and driven wheels. The propulsion means may assist in moving the tool platform along the seabed, and / or reducing the turning circle thereof.

[0028] The subsea soil preparation device may comprise thermal resistance sensors configured to measure thermal resistance of the soil of the seabed, preferably wherein the thermal resistance sensors are connected with the plurality of retractable blades. Particularly, the thermal properties of the soil may have an effect on the utilities that are to be installed in the seabed, which may affect which material is to be used to burrow the utilities. For instance, if the utilities may become too hot during use it is more favorable to have soil with decent conductivity for heat, such that the utilities (e.g., cables) can sufficiently transfer heat away. In case it is determined that the thermal properties of the seabed are not optimal, it may be necessary to provide other materials to cover the utilities. Such materials need to be brought in from other locations, such that it is beneficial to be aware of this requirement before the trenching or digging operations have started, for improved logistics.

[0029] The subsea soil preparation device may comprise a cutter configured to cut through linear obstructions, such as anchor chains or cables, preferably wherein the cutter is a hydraulic cutter. For instance, an old obsolete cable may have been left in the seabed. The cutter can prevent the future digger or trencher from getting tangled in such cable.

[0030] The tool platform may comprise a front platform part and a rear platform part, wherein the front platform part and the rear platform part are connected through a hinged connection. The hinged connection may be controllable, for instance by means of an actuator, such as a hydraulic actuator, to decrease the turning circle of the tool platform and to control the track of the tool. The disclosure further comprises, according to a second aspect, a soil preparation system, comprising a towing vessel and a subsea soil preparation device according to the first aspect, wherein the subsea soil preparation device is connected to the towing vessel through a tow.

[0031] BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Several aspects of the present disclosure are further elucidated through the following figures, wherein:

[0033] FIG. 1 shows a soil preparation system constituting a vessel that tows a soil preparation device along the seabed;

[0034] FIGS. 2 - 5 show side views of a soil preparation device, wherein blades are shown in different positions;

[0035] FIG. 6 shows a perspective view of the soil preparation device, with the blades in retracted position;

[0036] FIGS. 7 - 10 show the soil preparation device in operation along a seabed in various positions;

[0037] FIG. 11 shows a perspective view of the soil preparation device in a position wherein the front and rear parts of the tool platform are angled with respect to each other through a hinge mechanism.

[0038] DETAILED DESCRIPTION

[0039] In FIG. 1 an overview of a soil preparation system is shown. The system is comprised of a vessel V, such as a ship, that is configured for towing by means of a tow T. The tow T is attached to a soil preparation device 1, also referred to as soil conditioning device 1 or simply conditioning device 1, that is positioned in the water W on the seabed SB. The vessel V is thus configured to pull the conditioning device 1 along the seabed SB to prepare the seabed SB for subsequent digging or trenching operations.

[0040] The soil preparation device 1 has a frame 2A, 2B composed of a front frame part 2A and a rear frame part 2B. The frame 2A, 2B as a whole may be referred to as a tool platform 2A, 2B. The front frame part 2 A is equipped with a soil combing tool 3, that comprises a plurality of retractable blades 30. When extended (not shown in FIG. 1), these blades 30 extend through slits 60 in a frontfacing shield 6, and into the seabed SB, which is explained in more detail below. The device 1 also comprises towing means 7 which provide an anchor point for the tow T. Naturally, the towing means 7 may comprise multiple anchor points for one or more tows T. As seen clearly in the magnified portion of FIG. 1, the blades 30 may also be equipped with frontfacingjet nozzles 32, that may be used for fluidization of the soil of the seabed SB, thereby allowing the retractable blades 30 to more easily move through jettable soils, such as sand. In addition, the jets 32 may aid in keeping the blades 30 clean from materials that tend to attach to the frontal surface of the blades 30.

[0041] The rear frame part 2B of the device 1 may be equipped with secondary soil combing tool 5 with a plurality of secondary blades 50. These secondary blades 50 can also be retracted. In the extended position, as shown in FIG. 1, the secondary blades extend at least partially into the seabed SB.

[0042] The rear frame part 2B may further be equipped with a rotatable cutting member 4 for loosening the soil of the seabed SB. The rotatable cutting member 4 is explained in further detail below.

[0043] FIG. 2 shows the soil preparation device 1 in a side view, wherein the retractable blades 30 and the secondary blades 50 are in their extended positions. The rotatable cutting tool 4 is also in its engaged position, wherein it is configured to extend into the seabed SB to perform a cutting operation. The rotatable cutting tool 4 may also be pivoted through a pivot mechanism 40 to a disengaged position (not shown), in which the rotation axis R of the cutting tool 4 is approximately parallel to the seabed SB or the longitudinal direction X of the device 1. The pivot mechanism 40 is preferably hydraulic.

[0044] As shown, in their extended position the blades 30 are inclined at an average angle a with respect to the longitudinal direction X of the device, which longitudinal direction X is - in use - substantially parallel to the seabed SB on which the device 1 is positioned. Note that the blades 30 are curved, such that the exact inclination angle varies along the length of the blades 30. Accordingly, the average angle a shown here is simply for illustrative purposes of the inclination of the blades 30. In the extended position, the blades 30 extend through slits 60 of the front-facing shield 6 of the device 1. The blades 30 may be extended and retracted through an actuation mechanism 31, that is preferably hydraulic.

[0045] The front frame part 2A and rear frame part 2B are each equipped with sliding means 20A, 20B that are configured to allow the frame 2A, 2B to be slid along the seabed SB. In the shown example of FIG. 2, both the front frame part 2A and the rear frame part 2B are equipped with two sliding means 20A, 20B which are each formed as ski-like elements. The front frame part 2A is further equipped with a towing means 7, here exemplified by a mounting hole 7. The front and rear frame parts 2 A, 2B are connected with each other through a hinge mechanism 8. This allows for the rear frame part 2B to pivot with respect to the front frame part 2A, particularly in the XY- plane, which improves (i.e., decreases) the turning circle of the conditioning device 1 and improves track control.

[0046] The secondary blades 50 are shown to be in the extended position, wherein they extend - in use of the device 1 - into the seabed SB. The secondary soil combing tool 5 is hingedly connected to the rear frame part 2B by means of a hinge mechanism 51, that is preferably hydraulic. In their extended position the secondary blades 50 are inclined at an average angle P with respect to the longitudinal direction X of the device, which longitudinal direction X is - in use - substantially parallel to the seabed SB on which the device 1 is positioned. Note that the secondary blades 50 are curved, such that the exact inclination angle varies along the length of the secondary blades 50. Accordingly, the average angle shown here is simply for illustrative purposes of the inclination of the secondary blades 50. Similar to the retractable blades 30, the secondary blades 50 transport objections that do not fit between the secondary blades 50 to the surface, due to their inclination P with respect to the seabed SB surface.

[0047] The rear frame part 2B is further equipped with a rear shield 9 for transporting obstructions, that are moved to the surface by the secondary blades 50, to the sides, i.e., in the Y-direction (positive and / or negative Y directions). The V- shape of the rear shield 9 ensures that the obstructions take the shortest path to the sides of the device 1, thus minimizing the amount of time movement resistance is causes by such obstructions.

[0048] FIG. 3 shows the device 1 of FIG. 2, wherein the retractable blades 30 are partially retracted and the secondary blades 50 are fully retracted. The rotatable cutting member 4 is in the engaged position still. A portion of the shield 6 that lies between the blades 30 and thus between the slits 60 is referred to as a unblocking member 61. The unblocking member 61 is suitable for dislodging material (such as obstructions, e.g., boulders or the like) that get stuck between the blades 30. Particularly, when an obstructions or the like cause a blockage between two blades 30, the blades 30 can be retracted until the blockage is pushed loose by the unblocking member 61. This ensures that blockages do not significantly hinder operations. Furthermore, it is noted that the shield 6 is V- shaped, such that obstructions that are pushed to the seabed SB surface by the blades 30 are pushed to the sides of the device 1, i.e., in the positive or negative Y-directions.

[0049] FIG. 4 shows the device 1 of FIGS. 2 and 3, wherein the blades 30 are tilted as compared to the extended position shown in FIG. 2. The tilted position of the blades 30 enable for heavy obstructions that fail to move to the surface by engagement with the inclined blades 30 as shown in FIG. 2 to be lifted to the surface of the seabed SB instead. The tilting mechanism is a part of the actuation mechanism 31, wherein it is noted that the tilting and retraction movements are independently controlled.

[0050] FIG. 5 finally shows a tilted and partially retracted position of the retractable blades 30.

[0051] In FIG. 6 the soil preparation device 1 is shown in in perspective view from a different perspective as FIGS. 2 - 5. This view reveals that the rear shield 9 also comprises slits 90 and unblocking members 91 formed therebetween, similar to the shield 6 paired with the soil combing tool 3. Accordingly, blockages between the blades 50 of the secondary soil combing tool 5 can also be resolved effectively.

[0052] FIGS. 7 - 10 show the soil preparation device in operation along a seabed SB in various positions. It can be seen that the device 1 prepares the soil of the seabed SB so as to form a preconditioned seabed section T, that is pre-cut and cleared from obstructions. Various obstructions, such as boulders B, are worked up to the surface by the retractable blades 30 as well as the secondary blades 50, and are subsequently moved to the sides of the device 1 by means of the front-facing shield 6 and the rear shield 9, respectively. Particularly large and heavy obstructions, such as the large boulder BL shown in FIG. 9, may be worked to the surface by tilting the blades 30. After lifting the large boulder B or the like to the surface of the seabed SB, the blades 30 may be tilted back to their extended and inclined positions (see, e.g., FIG. 2) after which the preconditioning operation may be resumed as shown, for instance, in FIGS. 7 and 8.

[0053] In FIG. 10, various components of the device 1 have been removed to show the purpose of the rotatable cutting member 4. As illustrated, the preconditioned seabed section T is, in this example, comprised of loosened soil, that has been loosened by the rotatable cutting member 4. For this purpose, the rotatable cutting member 4 is brought into the engaged position (as shown), wherein the rotation axis is roughly perpendicular to the surface of the seabed SB, or in the Z-direction. This soil loosening procedure is optional, as the rotatable cutting member 4 can also be positioned in its disengaged position, wherein the rotation axis R is roughly horizontal, i.e., parallel to the surface of the seabed SB, such that it does not engage the seabed SB.

[0054] In FIG. 11 the purpose of the hinge mechanism 8 that connects the front frame part 2A and the rear frame part 2B is illustrated. In this perspective view, the front frame part 2A and rear frame part 2B are hinged with respect to each other in the XY-plane, such that the forward direction Fi of the front frame part 2A and the forward direction Fz of the rear frame part 2B differ from each other by an hinge angle y. Accordingly, the device 1 is able to make a tighter turning radius as compared to a rigidly connected front frame part 2A and rear frame part 2B, and the track can be actively controlled.

[0055] The figures and the description thereof presented herein are not to be construed as limiting the scope of the disclosure, particularly the claims, to any extent, but merely as illustrative examples used to elucidate the present disclosure and invention(s) described therein.

[0056] The disclosure comprises the following clauses:

[0057] CLAUSES

[0058] 1. Subsea soil preparation device (1), comprising: a tool platform (2A, 2B), configured to be placed on and move along a seabed (SB); a soil combing tool (3) connected with the tool platform (2A, 2B), the soil combing tool (3) comprising a plurality of retractable blades (30), with at least an extended position and a retracted position, wherein, in the extended position of the plurality of retractable blades (30), at least a part of each of the plurality of retractable blades (30) extends into the seabed (SB) on which the tool platform (2A, 2B) is positioned, and at least in the extended position, the part of each of the plurality of retractable blades (30) that extends into the seabed (SB) is inclined with respect to the seabed (SB), and extends away from the tool platform (2A, 2B) in a front-facing direction.

[0059] 2. Subsea soil preparation device (1) according to clause 1, wherein, in the retracted position of the plurality of retractable blades (30), the plurality of retractable blades (30) extends at least partially above the seabed (SB) on which the tool platform is positioned, and preferably fully above the seabed (SB) on which the tool platform is positioned.

[0060] 3. Subsea soil preparation device (1) according to clause 1 or 2, wherein the soil combing tool further comprises a unblocking member (61) arranged between at least two of the plurality of retractable blades (30) in the extended position thereof.

[0061] 4. Subsea soil preparation device (1) according to clause 3, wherein the unblocking member (61) comprises a front-facing shield (6) with a plurality of slits (60), wherein, each of the plurality of retractable blades (30) extend through a respective one of the plurality of slits (60) in the extended position of the plurality of retractable blades (30). 5. Subsea soil preparation device (1) according to clause 4, wherein the front-facing shield (6) comprises one or more inclined surfaces having an inclination angle with respect to the frontfacing direction.

[0062] 6. Subsea soil preparation device (1) according to clause 5, wherein the front-facing shield (6) comprises two of the one or more inclined surfaces, wherein the two inclined surfaces form a V-shaped shield (6) pointing in the front-facing direction.

[0063] 7. Subsea soil preparation device (1) according to any one of the preceding clauses, wherein the plurality of retractable blades (30) is tiltable with respect to the tool platform (2A, 2B).

[0064] 8. Subsea soil preparation device (1) according to any one of the preceding clauses, further comprising an active cutting member (4) connected with the tool platform (2A, 2B) and configured to engage the seabed (SB).

[0065] 9. Subsea soil preparation device (1) according to clause 8, wherein the active cutting member (4) is tiltable between at least an engaged and a disengaged position, wherein in the engaged position the active cutting member (4) engages the seabed (SB), and preferably wherein in the disengaged position the active cutting member (4) does not engage the seabed (SB).

[0066] 10. Subsea soil preparation device (1) according to clause 9, wherein, in the engaged position, the active cutting member (4) extends at least partially into the seabed (SB).

[0067] 11. Subsea soil preparation device (1) according to any one of clauses 8 - 10, wherein the plurality of retractable blades (30) is positioned at a distance from the active cutting member (4) in the front-facing direction, such that the active cutting member (4) is located behind the plurality of retractable blades (30).

[0068] 12. Subsea soil preparation device (1) according to any one of clauses 8 - 11, wherein the active cutting member (4) is a rotatable cutting member (4), preferably wherein in the engaged position a rotation axis (R) of the rotatable cutting member (4) is substantially perpendicular to the seabed (SB), and preferably wherein in the disengaged position the rotation axis (R) is substantially parallel to the seabed (SB).

[0069] 13. Subsea soil preparation device (1) according to any one of the preceding clauses, wherein the soil combing tool comprises a front-facing jet nozzle (32) configured to generate a fluid jet stream directed substantially in the front-facing direction, preferably wherein at least one of the plurality of retractable blades (30) comprises the front-facing jet nozzle (32).

[0070] 14. Subsea soil preparation device (1) according to any one of the preceding clauses, the soil combing tool further comprising a plurality of secondary blades (50) connected to the tool platform (2A, 2B), and wherein the plurality of retractable blades (30) is positioned at a distance from the plurality of secondary blades (50) in the front-facing direction, such that the plurality of secondary blades (50) is located behind the plurality of retractable blades (30).

[0071] 15. Subsea soil preparation device (1) according to clause 14, wherein the plurality of secondary blades (50) is retractable, with at least an extended position and a retracted position, wherein, in the extended position of the plurality of secondary blades (50), the plurality of secondary blades (50) extend at least partially into the seabed (SB) on which the tool platform (2A, 2B) is positioned, and preferably wherein in the retracted position of the plurality of secondary blades (50), the plurality of secondary blades (50) extends at least partially above the seabed (SB) on which the tool platform (2A, 2B) is positioned, and further preferably fully above the seabed (SB) on which the tool platform (2A, 2B) is positioned.

[0072] 16. Subsea soil preparation device (1) according to clause 14 or 15, wherein a first distance between each of the plurality of retractable blades (30) in a direction perpendicular to the frontfacing direction is larger than a second distance between each of the plurality of secondary blades (50) in a direction perpendicular to the front-facing direction.

[0073] 17. Subsea soil preparation device (1) according to any one of clauses 14 - 16, wherein the plurality of retractable blades (30) and / or the plurality of secondary blades (50) comprise force sensors configured to measure a movement resistance.

[0074] 18. Subsea soil preparation device (1) according to clause 17, wherein the plurality of retractable blades (30) and / or the plurality of secondary blades (50) are connected to the tool platform (2A, 2B) through at least one hydraulic mechanism (31, 51), and wherein the force sensors comprise pressure sensors configured to measure a hydraulic pressure in the at least one hydraulic mechanism (31, 51).

[0075] 19. Subsea soil preparation device (1) according to clause 17 or 18, wherein both the plurality of retractable blades (30) and the plurality of secondary blades (50) comprise the force sensors, such that the plurality of retractable blades (30) measure movement resistant before soil preparation and the plurality of secondary blades (50) measure movement resistance after soil preparation.

[0076] 20. Subsea soil preparation device (1) according to any one of the preceding clauses, comprising means (7) for attaching a tow (T), such that the subsea soil preparation device (1) may be towed along the seabed (SB) by a vessel (V).

[0077] 21. Subsea soil preparation device (1) according to any one of the preceding clauses, wherein at least part of the tool platform (2A, 2B) is formed as a sled such that the tool platform (2A, 2B) may slide along the seabed (SB), preferably comprising two ski-like elements (20A, 20B) extending substantially in the front-facing direction.

[0078] 22. Subsea soil preparation device (1) according to any one of the preceding clauses, further comprising propulsion means, preferably wherein the propulsion means comprise at least one of a hydrojet, a propeller, driven tracks, and driven wheels.

[0079] 23. Subsea soil preparation device (1) according to any one of the preceding clauses, further comprising thermal resistance sensors configured to measure thermal resistance of the soil of the seabed (SB), preferably wherein the thermal resistance sensors are connected with the plurality of retractable blades (30).

[0080] 24. Subsea soil preparation device (1) according to any one of the preceding clauses, further comprising a cutter configured to cut through linear obstructions, such as anchor chains or cables, preferably wherein the cutter is a hydraulic cutter.

[0081] 25. Subsea soil preparation device (1) according to any one of the preceding clauses, wherein the tool platform (2A, 2B) comprises a front platform part (2A) and a rear platform part (2B), wherein the front platform part (2A) and the rear platform part (2B) are connected through a hinged connection (8).

[0082] 26. Soil preparation system, comprising a towing vessel (V) and a subsea soil preparation device (1) according to any one of the preceding clauses, wherein the subsea soil preparation device (1) is connected to the towing vessel (V) through a tow (T).

Claims

CLAIMS1. Subsea soil preparation device (1), comprising: a tool platform (2 A, 2B), configured to be placed on and move along a seabed (SB); a soil combing tool (3) connected with the tool platform (2A, 2B), the soil combing tool (3) comprising a plurality of retractable blades (30), with at least an extended position and a retracted position, wherein, in the extended position of the plurality of retractable blades (30), at least a part of each of the plurality of retractable blades (30) extends into the seabed (SB) on which the tool platform (2A, 2B) is positioned, and at least in the extended position, the part of each of the plurality of retractable blades (30) that extends into the seabed (SB) is inclined at an inclination angle (a) with respect to the seabed (SB), and extends away from the tool platform (2A, 2B) in a frontfacing direction, characterized in that the retractable blades (30) are configured to be extended and retracted relative to the tool platform (2 A, 2B) through an actuation mechanism (31), wherein the actuation mechanism (31) is configured to extend and retract the retractable blades (30) whilst substantially maintaining the inclination angle (a) within an inclination range.

2. Subsea soil preparation device (1) according to claim 1, wherein, in the retracted position of the plurality of retractable blades (30), the plurality of retractable blades (30) extends at least partially above the seabed (SB) on which the tool platform is positioned, and preferably fully above the seabed (SB) on which the tool platform is positioned.

3. Subsea soil preparation device (1) according to claim 1 or 2, wherein the soil combing tool further comprises an unblocking member (61) configured to reach between at least two of the plurality of retractable blades (30) in the extended position and / or the retracted position thereof.

4. Subsea soil preparation device (1) according to claim 3, wherein the unblocking member (61) is arranged between at least two of the plurality of retractable blades (30) in the extended position thereof.

5. Subsea soil preparation device (1) according to claim 4, wherein the unblocking member (61) comprises a front-facing shield (6) with a plurality of slits (60), wherein, eachof the plurality of retractable blades (30) extend through a respective one of the plurality of slits (60) in the extended position of the plurality of retractable blades (30).

6. Subsea soil preparation device (1) according to claim 5, wherein the front-facing shield (6) comprises one or more inclined surfaces having an inclination angle with respect to the front-facing direction.

7. Subsea soil preparation device (1) according to claim 6, wherein the front-facing shield (6) comprises two of the one or more inclined surfaces, wherein the two inclined surfaces form a V-shaped shield (6) pointing in the front-facing direction.

8. Subsea soil preparation device (1) according to any one of the preceding claims, wherein the plurality of retractable blades (30) is tiltable with respect to the tool platform (2A, 2B).

9. Subsea soil preparation device (1) according to any one of the preceding claims, further comprising an active cutting member (4) connected with the tool platform (2A, 2B) and configured to engage the seabed (SB).

10. Subsea soil preparation device (1) according to claim 9, wherein the active cutting member (4) is tiltable between at least an engaged and a disengaged position, wherein in the engaged position the active cutting member (4) engages the seabed (SB), and preferably wherein in the disengaged position the active cutting member (4) does not engage the seabed (SB).

11. Subsea soil preparation device (1) according to claim 10, wherein, in the engaged position, the active cutting member (4) extends at least partially into the seabed (SB).

12. Subsea soil preparation device (1) according to any one of claims 9 - 11, wherein the plurality of retractable blades (30) is positioned at a distance from the active cutting member (4) in the front-facing direction, such that the active cutting member (4) is located behind the plurality of retractable blades (30).

13. Subsea soil preparation device (1) according to any one of claims 9 - 12, wherein the active cutting member (4) is a rotatable cutting member (4), preferably wherein in the engaged position a rotation axis (R) of the rotatable cutting member (4) is substantiallyperpendicular to the seabed (SB), and preferably wherein in the disengaged position the rotation axis (R) is substantially parallel to the seabed (SB).

14. Subsea soil preparation device (1) according to any one of the preceding claims, wherein the soil combing tool comprises a front-facing jet nozzle (32) configured to generate a fluid jet stream directed substantially in the front-facing direction, preferably wherein at least one of the plurality of retractable blades (30) comprises the front-facing jet nozzle (32).

15. Subsea soil preparation device (1) according to any one of the preceding claims, the soil combing tool further comprising a plurality of secondary blades (50) connected to the tool platform (2A, 2B), and wherein the plurality of retractable blades (30) is positioned at a distance from the plurality of secondary blades (50) in the front-facing direction, such that the plurality of secondary blades (50) is located behind the plurality of retractable blades (30).

16. Subsea soil preparation device (1) according to claim 15, wherein the plurality of secondary blades (50) is retractable, with at least an extended position and a retracted position, wherein, in the extended position of the plurality of secondary blades (50), the plurality of secondary blades (50) extend at least partially into the seabed (SB) on which the tool platform (2A, 2B) is positioned, and preferably wherein in the retracted position of the plurality of secondary blades (50), the plurality of secondary blades (50) extends at least partially above the seabed (SB) on which the tool platform (2A, 2B) is positioned, and further preferably fully above the seabed (SB) on which the tool platform (2A, 2B) is positioned.

17. Subsea soil preparation device (1) according to claim 15 or 16, wherein a first distance between each of the plurality of retractable blades (30) in a direction perpendicular to the front-facing direction is larger than a second distance between each of the plurality of secondary blades (50) in a direction perpendicular to the front-facing direction.

18. Subsea soil preparation device (1) according to any one of claims 15 - 17, wherein the plurality of retractable blades (30) and / or the plurality of secondary blades (50) comprise force sensors configured to measure a movement resistance.

19. Subsea soil preparation device (1) according to claim 18, wherein the plurality of retractable blades (30) and / or the plurality of secondary blades (50) are connected to the tool platform (2A, 2B) through at least one hydraulic mechanism (31, 51), and wherein the force sensors comprise pressure sensors configured to measure a hydraulic pressure in the at least one hydraulic mechanism (31, 51).

20. Subsea soil preparation device (1) according to claim 18 or 19, wherein both the plurality of retractable blades (30) and the plurality of secondary blades (50) comprise the force sensors, such that the plurality of retractable blades (30) measure movement resistant before soil preparation and the plurality of secondary blades (50) measure movement resistance after soil preparation.

21. Subsea soil preparation device (1) according to any one of the preceding claims, comprising means (7) for attaching a tow (T), such that the subsea soil preparation device (1) may be towed along the seabed (SB) by a vessel (V).

22. Subsea soil preparation device (1) according to any one of the preceding claims, wherein at least part of the tool platform (2A, 2B) is formed as a sled such that the tool platform (2A, 2B) may slide along the seabed (SB), preferably comprising two ski-like elements (20A, 20B) extending substantially in the front-facing direction.

23. Subsea soil preparation device (1) according to any one of the preceding claims, further comprising propulsion means, preferably wherein the propulsion means comprise at least one of a hydrojet, a propeller, driven tracks, and driven wheels.

24. Subsea soil preparation device (1) according to any one of the preceding claims, further comprising thermal resistance sensors configured to measure thermal resistance of the soil of the seabed (SB), preferably wherein the thermal resistance sensors are connected with the plurality of retractable blades (30).

25. Subsea soil preparation device (1) according to any one of the preceding claims, further comprising a cutter configured to cut through linear obstructions, such as anchor chains or cables, preferably wherein the cutter is a hydraulic cutter.

26. Subsea soil preparation device (1) according to any one of the preceding claims, wherein the tool platform (2A, 2B) comprises a front platform part (2A) and a rearplatform part (2B), wherein the front platform part (2A) and the rear platform part (2B) are connected through a hinged connection (8).

27. Soil preparation system, comprising a towing vessel (V) and a subsea soil preparation device (1) according to any one of the preceding claims, wherein the subsea soil preparation device (1) is connected to the towing vessel (V) through a tow (T).

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